A color diffusion transfer photographic process is well known which utilizes an azo dye-providing compound releasing an azo dye as a result of development under basic conditions, with the azo dye having a different diffusibility from that of the azo dye-providing compound itself. Dye-providing compounds releasing a cyan dye, for example, are described in U.S. Pat. Nos. 3,942,987, 4,013,635, 4,273,708, 4,268,625 and Japanese Patent Application (OPI) No. 143323/78 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application").
All the compounds described in the foregoing references have a nitro group in the para-position to the azo group and it is known that they are subject to discoloration through reduction of the nitro group during the developing process. Moreover, in general, azo dyes having a nitro group necessarily provide images inferior in light fastness because of their light reducing properties.
It is sometimes observed that the dye-providing compounds, when incorporated into the same layer as a light-sensitive silver halide emulsion, inhibit development of the silver halide. This is assumed to be ascribable to the presence of the nitro group.
Japanese Patent Application (OPI) No. 66227/78 discloses cyan azo dye-providing compounds having a trifluoromethanesulfonyl group in the para-position to the azo group. These compounds, however, have disadvantages relating to synthesis and pollution since they contain fluorine. In addition, they require improvement in the sharpness of hue and diffusibility of dye released.
British Pat. No. 1,490,248 and Japanese Patent Application (OPI) No. 40402/80 disclose magenta azo dye-providing compounds with a diazo component having a plurality of alkylsulfonyl groups. All the compounds are unsubstituted or substituted by an electron attractive group in the 2-position of naphthol and, therefore, their absorption peaks are present at such short wavelengths that they cannot be used as cyan dye-providing compounds.
Until now, no cyan dye-providing compound apart from those having a nitro or trifluoromethanesulfonyl group in the para-position to the azo group has been known.